XDocument Class

Dim output As New StringBuilder
Dim srcTree As XDocument = _
    <?xml version="1.0" encoding="utf-8" standalone="yes"?>
    <!--This is a comment-->
    <Root>
        <Child1>data1</Child1>
        <Child2>data2</Child2>
        <Child3>data3</Child3>
        <Child2>data4</Child2>
        <Info5>info5</Info5>
        <Info6>info6</Info6>
        <Info7>info7</Info7>
        <Info8>info8</Info8>
    </Root>
Dim doc As XDocument = _
    <?xml version="1.0" encoding="utf-8" standalone="yes"?>
    <!--This is a comment-->
    <Root>
        <%= From el In srcTree.<Root>.Elements _
            Where CStr(el).StartsWith("data") _
            Select el %>
    </Root>
output.Append(doc)
output.Append(Environment.NewLine)

OutputTextBlock.Text = output.ToString()

StringBuilder output = new StringBuilder();
XDocument srcTree = new XDocument(
    new XComment("This is a comment"),
    new XElement("Root",
        new XElement("Child1", "data1"),
        new XElement("Child2", "data2"),
        new XElement("Child3", "data3"),
        new XElement("Child2", "data4"),
        new XElement("Info5", "info5"),
        new XElement("Info6", "info6"),
        new XElement("Info7", "info7"),
        new XElement("Info8", "info8")
    )
);

XDocument doc = new XDocument(
    new XComment("This is a comment"),
    new XElement("Root",
        from el in srcTree.Element("Root").Elements()
        where ((string)el).StartsWith("data")
        select el
    )
);
output.Append(doc + Environment.NewLine);

OutputTextBlock.Text = output.ToString();